The World Wide Web (the "Web") is a graphical hypertext-based interface that enables users to quickly move between Web sites and Web documents, also known as Web pages, on the Internet by following links to other Web documents or Web sites (Web pages) embedded within a Web document (Web page).
Creating a Web Document
A Web document may contain many forms of information, including text, graphics, video, audio, and links to other Web documents anywhere in the world. Presently, Hypertext Mark-up Language (HTML) is the standard format for documents on the World Wide Web. An HTML formatted document has HTML codes, i.e., commands, embedded in the document.
A software application known as a Web browser is used to access documents on the Web. By understanding HTML, Web browser software can properly display a Web document on a user's output display device. More importantly, Web browser software interprets the HTML commands in an HTML formatted Web document to navigate a link in that Web document to another Web document. The Web browser thereby provides automatic access to other Web documents on the Web.
A user with an understanding of HTML can create an HTML formatted Web document using any text editor software application, e.g., SimpleText, available from Apple Computer, Inc. SimpleText is a basic American Standard Code for Information Interchange (ASCII) text editor application. However, the user has to embed HTML "tags" in the Web document.
HTML tags are inserted at the appropriate locations in a Web document to inform a Web browser how to display the various kinds of information in the Web document. For example, FIG. 2 illustrates an HTML formatted document 200. The document is interpreted and displayed on a user's output display device using a Web browser such as Netscape Navigator', available from Netscape Communications, Inc. FIG. 3 shows the display 300 of the HTML document in FIG. 2 on an Apple Macintosh computer system using Netscape Navigator' Web browser software.
HTML tags are typically paired. For example, the pair of tags "&lt;html&gt;" and "&lt;/html&gt;" on lines 1 and 9 of FIG. 1 identifies the information contained between the tags as an HTML document. The HTML document is comprised of a header indicated by the pair of tags "&lt;head&gt;" and "&lt;/head&gt;" on lines 1 and 2, and a body indicated by the pair of tags "&lt;body&gt;" and "&lt;/body&gt;" on lines 2 and 8, respectively.
The pair of "&lt;h122 " and "&lt;/h122 " on line 3 indicates a heading. Headings are numbered one through six, in order of decreasing font size. The text on line 4 ends with the end of paragraph tag "&lt;P&gt;". Upon detecting the end of a paragraph, a Web browser inserts a carriage return and a linefeed.
A horizontal rule tag, "&lt;HR&gt;", appears on line 5 of the HTML document. A Web browser inserts a horizontal line across the output display device upon encountering this tag. As can be seen from the example HTML document in FIG. 1, editing a very simple Web document using a plain editor requires an understanding of HTML and careful attention to syntax.
Tag-based editors, also known as HTML editors, were developed to provide HTML extensions. The HTML extensions allow a user to edit a document, select a segment of the document and choose an appropriate HTML tag from a pull down menu or the like to insert the HTML tags around the selected segment of the document. This obviates the need for a user to learn the specific keystroke sequences representing a given pair of HTML tags. However, there is still a significant difference between what the user sees in an HTML document such as illustrated in FIG. 1, and the corresponding display illustrated in FIG. 2. Thus, a certain level of user-sophistication and trial and error is required to generate a Web document as desired by the user. To that end, more recent HTML editors known as What You See Is What You Get (WYSIWYG) editors have been employed to generate Web documents.
WYSIWYG HTML editors, such as WebMagic, available from Silicon Graphics, Incorporated, FrontPage, available from Vermeer Technologies, Incorporated, and Adobe PageMill, available from Adobe Systems, Incorporated, simplify the task of creating a Web page by presenting the user's working page, i.e., a Web page being created by the user, as it would appear when accessed by a Web browser. In constructing the page, changes can be made by simple direct manipulation, as in a traditional word processor software application such as MacWrite, available from Claris Corp. WYSIWYG editors remove the need for users to correctly formulate the syntax and structure of a Web document and allow greater attention to be paid to the visual appeal and format of the final Web document.
WYSIWYG editors are quite limited, however, by several structural features of HTML and the Web. One limitation is that the range of Web browsers and platforms is as variable as the range of all computers, meaning that the visual presentation provided by a WYSIWYG editor will be appropriate for only a subset of the possible audiences of the document. A second limitation is that HTML is a rapidly evolving language with new features appearing every month, requiring expensive rewrites of WYSIWYG editors when major new features such as tables or frames appear. A third limitation is that WYSIWYG editors do nothing to expose the underlying programmatic structure of an HTML document. For these reasons, many intermediate and nearly all expert users of HTML produce their documents "in the raw" without using a WYSIWYG editor. Thus, what is needed is a method for creating Web documents that removes the need to understand HTML syntax while allowing the user to easily discern the format of the Web document as displayed on an output display device.
Publishing a Web Document
With reference to FIG. 8, a simplified model of the elements comprising the World Wide Web (the "Web") on the Internet is depicted. The Web 810 is a graphical, hypertext-based interface that overlays the Internet. The Internet is a collection of interconnected, autonomous data communication networks which spans the globe. A user at a computer system executing a Web browser software application such as Netscape Navigator can access information in the form of Web documents or pages on the Web. The information may reside on the same or different computer system or systems. This model is often referred to as a client-server computing model, in which one or more clients 810 and 820 access or query a server 830 over a data communications network.
A server on the Web serves, or publishes, Web documents over the Web. The documents are available to a user who accesses the server from a client executing Web browser application software. The server and client communicate using a communications protocol. Typically, a server and client communicate over a data communications network underlying the Web using an International Standards Organization (ISO) Open Systems Interconnection (OSI) Application-layer protocol such as HyperText Transfer Protocol (HTTP). The Application-layer protocol provides a method of communicating ASCII-based, HTML-formatted information comprising a Web document published by a server. The Web document is transmitted over a data communications network to a client upon request from the client. The HTTP protocol, as an Application-layer protocol, utilizes the services of a standard set of OSI Transport-layer and Network-layer data communication protocols such as the Transport Control Protocol/Internet Protocol (TCP/IP) suite of data communication protocols.
A client on the Web is comprised of a computer system executing Web browser application software. The client communicates with the server using HTTP, but must understand HTML as well, so that, among other things, upon receiving an HTML document from the server, the client knows how to display the document on an attached output display device.
As described above, HTML documents have traditionally been plain ASCII text files with HTML tags inserted at appropriate locations within the text file. The files are stored in a file system, as depicted in FIG. 9. FIG. 9 illustrates a traditional hierarchical file system 900 having a hierarchical directory structure 901 by which files, e.g., file A (902), are organized on a permanent storage medium such as a magnetic disk. File C 903 is a subdirectory containing files X, Y and Z. File Z 905 is a subdirectory as well for files 1, 2 and 3.
A server running the HTTP, i.e., an HTTP server, receives a request from a client for a particular HTML document. The HTTP server scans its file system directory 901 in search of the data file or files storing the HTML document. Upon locating the file or files in the file system, the HTTP server transmits the contents of the file using the HTTP. Thus, the HTTP server has no knowledge, and in fact, needs no knowledge, of the content or format of the HTML document to publish, i.e., transmit, the HTML document to the client over the data communications network.
A disadvantage in the above approach is that the contents of the HTML document are static. In other words, the contents of the HTML document do not change once created by an editor until such time as the document is directly modified by a user via an editor. To overcome this limitation, Common Gateway Interface Binary (CGI-bin) scripts were developed, which are essentially perl, C or C++ computer programs that output HTML-formatted ASCII text at run time. CGI-bin scripts allowed a server to generate content within an HTML document "on the fly," i.e., dynamically, depending upon the current state of the server, e.g., the date or time of day, or input from a user. The information provided as input from a user could be information obtained from a client through an HTTP request, e.g., information regarding who or where the user is located, security or access control information, etc.
As opposed to HTML documents, HTTP servers do need to understand a CGI-bin script insofar as a server must know where the scripts are located, how to execute the scripts, and how to receive the information output by the script and convert the information, if necessary, to HTML format before transmitting it to a client over the data communications network.
One disadvantage of CGI-bin scripts is the level of user sophistication required to develop the scripts due to the computer program-like nature of the script language. Moreover, the scripts must be compiled, and are also limited in that they output ASCII text which must then be converted by the HTTP server or some other process to the appropriate format for a Web document, e.g., HTML format. Additionally, the scripts are created independent of each other, making it difficult and time-consuming to establish links between different CGI-bins scripts. What is needed is an object oriented-based authoring and serving environment wherein everything is treated as an object and an object can send messages to other objects or alter the serving environment itself. Finally, scripts cannot be easily extended and specialized like objects can. What is needed is a way for a user to take a certain object and create a specialized subclass that worked in exactly the same manner except for a different feature depending on the conditions.